1. Field of the Invention
The present disclosure relates to a zinc air fuel cell with enhanced cell performance.
2. Description of the Related Art
A zinc air fuel cell (ZAFC) is one of fuel cells which may replace internal combustion engines and lead acid batteries because the zinc air fuel cell can provide high energy efficiency as a next-generation cell with lightness and compactness. The zinc air fuel cell has several advantages that it produces stable discharge voltage, it maintains good performance and durability, it is environmentally friendly without producing harmful pollutants, it does not need fuel compression, and its manufacturing cost is low.
In operation of the zinc air fuel cell, zinc metals are provided as fuels, air is provided as an oxygen source, and aqueous alkaline solution is provided as an electrolyte. Zinc metals are ionized into zinc cations (Zn2+) in aqueous alkaline solution to generate electrons, which are transferred to an anode current collector, and move to a cathode current collector through an outside circuit. Oxygen is supplied to the cathode side and reacts with H2O and electrons on the cathode catalysts forming hydroxyl ions (OH−), and the hydroxyl ions move to the anode current collector through the electrolyte by concentration gradient. Then the hydroxyl ions react with zinc cations to form zinc oxides as the final product. According to this reaction scheme, the oxidation of zinc and the reduction of oxygen cause the change of chemical energy into electrical energy.
In the past, numerous studies on the zinc air fuel cell have been focused on the battery shape. Early studies proposed a zinc air fuel cell where a used zinc electrode was replaced with a new one, so that it was similar to a mechanically rechargeable secondary battery. Thereafter, studies have been performed on modified zinc air fuel cells which provide zinc pellets as the zinc fuel. Irrespective of cell-shapes, a few studies have been performed on the air cathode, especially on appropriate rare metal catalysts of cathode which may possess excellent oxygen reduction activities.
Hence, during investigation on zinc air fuel cells, the present inventors, to bring the present invention to completion, developed a zinc air fuel cell with enhanced cell performance by using a separator-electrode assembly, in which a cathode current collector, a catalyst-coated carbon paper, a separator, and an anode current collector are integrally combined, and also by using low-priced metal oxides as catalysts and low-priced NYLON™ (a generic designation for a family of polyamides trademarked by DuPont) filters as separators in the separator-electrode assembly.